Blossom End Rot in Tomatoes

[Ridgerunner]

As Seed and Monty said, soil pH and moisture has a whole lot to do with it. Especially if you have a clay soil, it is highly unlikely calcium in the soil is the problem. It's probably too much or too little water, with soil pH being another potential factor. People get stuck on the thought that it is the calcium in the soil, but usually that is not the problem, water is.

 

[bills]

As mentioned, egg shells will take quite a long time to make a difference. I use Bone Meal. It is finely ground, and can be used quite rapidly by the plants.

BER has not been an for me, perhaps because of the bone meal.. It's late season blight that usually kicks my butt. Seems to always occur after the first few cooler nights in the late summer, and prevents a good final harvest.
I destroy the plants, (fire) and try ripening the fruit off the plants. The green fruit, around 70% of it turns dark, and have to be tossed. Any that had just started to turn red when the blight first hit, will usually ripen up just fine still, and are still tasty.